000
FXUS65 KSLC 292140
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
340 PM MDT WED JUL 29 2015
.SYNOPSIS...STRONG HIGH PRESSURE WILL PREVAIL ACROSS THE REGION
THROUGH THE FIRST PART OF NEXT WEEK. A NORTHEAST SHIFT OF THIS
HIGH WILL ALLOW A MODEST SURGE OF SUB-TROPICAL MOISTURE TO SPREAD
NORTHEAST ACROSS THE AREA BEGINNING SATURDAY.
&&
.SHORT TERM (THROUGH 12Z SATURDAY)...A BROAD UPPER RIDGE REMAINS IN
PLACE ACROSS THE AREA THIS AFTN EXTENDING FROM A HIGH CENTERED
OVER THE SRN PLAINS STATES WEST NORTHWESTWARD OFF THE NRN CA
COAST. MOISTURE IS POOLED TO THE SOUTH OF THIS RIDGE OVER AZ AND A
LITTLE OF THIS IS BEGINNING TO SEEP INTO FAR SOUTHERN UTAH AT MID
LEVELS.
THE AIRMASS WARMING WILL CONTINUE ACROSS NORTHERN AND CENTRAL UTAH
WITH THE HIGH OVER THE AREA THROUGH SATURDAY.
THE RIDGE AXIS IS FORECAST TO DRIFT SLOWLY NWD THRU FRI AND MOISTURE
WILL CONTINUE TO SEEP NORTHWARD MAINLY AT MID LEVELS WITH THE LOWER
LEVELS STAYING FAIRLY DRY. THE EXCEPTION TO THIS WOULD BE OVER FAR
SERN UT AS A SMALL LOW DRIFTS OUT OF AZ THRU THE RIDGE AND ACROSS
FAR SERN UT ON FRI.
THIS INCREASING MOISTURE WOULD BRING AN INCREASE IN CONVECTION TO
THE FAR SERN CWA THU AFTN AND ACROSS MORE OF THE SOUTH FRI. MOST OF
THESE STORMS WILL BE ON THE DRY SIDE WITH GUSTY WINDS AND LIGHTNING
BUT NOT MUCH RAIN. THE FAR SERN CWA COULD SEE WETTER STORMS WHERE
MOISTURE IS FORECAST TO BE A LITTLE DEEPER.
.LONG TERM (AFTER 12Z SATURDAY)...GLOBAL MODELS REMAIN IN GOOD
AGREEMENT REGARDING A NET NORTHEASTERLY SHIFT OF THE RIDGE AXIS
ACROSS THE FORECAST AREA LATE SATURDAY THROUGH SUNDAY. SAID SHIFT
WILL ALLOW THE MORE MODEST SUBTROPICAL MOISTURE CURRENTLY PINNED
ALONG AND SOUTH OF THE UT/AZ BORDER TO ADVECT NORTH/NORTHEAST AS
MID LEVEL STREAMLINES BECOME MORE SOUTHERLY ORIENTED. INCREASING
SPREAD IN GUIDANCE DEVELOPS SUNDAY THROUGH MONDAY REGARDING
FORMATION AND EVOLUTION OF RETURN FLOW WAVES THAT WOULD ENHANCE
CONVECTIVE POTENTIAL THROUGH THAT TIME. THE 12Z ECMWF BECAME QUITE
BULLISH WITH ONCE SUCH FEATURE OWING TO HIGHER AND MORE AREALLY
EXPANSIVE QPF DURING THAT TIME. CONFIDENCE NOT HIGH REGARDING THIS
AND HAVE OPTED TO NOT CHANGE POPS OR TEMPS MUCH FROM THE PREVIOUS
PACKAGE. THE EC SOLUTION WOULD BE BOTH WETTER AND MUCH COOLER COME
MONDAY.
REGARDING THE MOISTURESURGE...BUFKIT PROFILES PORTRAY THE MORE
ELEVATED PWAT WILL REMAIN FAIRLY ELEVATED AND INSTABILITY PROFILES
SUPPORT MORE OF A LIGHTER RAIN/GUSTY WIND THREAT WITH CONVECTION
VERSUS A HEAVY RAIN THREAT ATTM. WILL CONTINUE TO MONITOR THIS
EVOLUTION IN FUTURE FORECASTS.
A DRYING SOUTHWESTERLY FLOW IS ANTICIPATED TO PUNCH INTO THE
EASTERN GREAT BASIN EARLY TO MID NEXT WEEK...THIS AS YET ANOTHER
CLOSED LOW TRANSITIONS OUT OF CENTRAL BRITCOL SOUTHEAST INTO THE
PACNW.
&&
.AVIATION...OPERATIONAL WEATHER CONCERNS WILL REMAIN MINIMAL AT
THE KSLC TERMINAL THROUGH THE VALID TAF PERIOD. NORTHWEST SURFACE
WINDS CURRENTLY IN PLACE WILL RETURN TO A LIGHT SOUTHEAST BETWEEN
03-04Z AND REMAIN IN PLACE THROUGH THE NIGHT. VFR CONDITIONS WILL
BE MAINTAINED UNDER LARGELY CLEAR SKIES.
&&
.FIRE WEATHER...HIGH PRESSURE WILL KEEP A DRY AND STABLE AIRMASS
ACROSS THE NORTHERN AND CENTRAL FIRE DISTRICT THROUGH THE FIRST PART
OF THIS WEEKEND. AFTERNOON HUMIDITY WILL DIP TO FAIRLY LOW VALUES
WITH POOR OVERNIGHT RECOVERIES. WINDS WILL BE MAINLY SLOPE DRIVEN
AND LIGHT TRANSPORT WINDS WILL KEEP CLEARING INDICES ON THE LOW SIDE
THROUGH THE WEEKEND. MOISTURE WILL INCREASE SOMEWHAT ACROSS THE FAR
SOUTH THURSDAY AND ACROSS MORE OF THE SOUTH FRIDAY BEFORE DRYING OUT
AGAIN SATURDAY. THIS BRINGS A THREAT OF ISOLATED MAINLY DRY
THUNDERSTORMS TO SOUTHEASTERN UTAH THURSDAY AFTERNOON AND ABOUT THE
SOUTHERN THIRD OF THE AREA FRIDAY. MOISTURE IS EXPECTED TO INCREASE
ACROSS MORE OF THE REGION AGAIN SUNDAY INTO MONDAY WITH THE THREAT
OF ISOLATED HIGH BASED SHOWERS AND MOSTLY DRY THUNDERSTORMS IN MOST
AREAS.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...NONE.
WY...NONE.
&&
$$
WILENSKY/MERRILL
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